Polyamide membranes and hollow fibers are used in a wide variety of reverse osmosis applications. The permselective properties of these membranes permit the purification of liquid streams to eliminate undesirable dissolved components. One important application is the purification of water used for industrial processes where dissolved components would contaminate process equipment or the product being prepared.
While currently available reverse osmosis units based on polyamide membranes are highly effective in their intended applications, the treatment of surface water such as that obtained from rivers and lakes has limited the useful life of such devices. The microorganisms found in such surface water tend to become imbedded and multiply in the polyamide membranes, causing clogging and fouling of the reverse osmosis unit. While a variety of disinfectants has been used to remove such microorganisms and inhibit their growth in other reverse osmosis membranes, most such disinfectants either rapidly degrade polyamide membranes or require an interruption of the operation of the reverse osmosis device. Accordingly, a need exists for the biological purification of reverse osmosis membranes based on an amide linkage during operation of the devices.